1. Field of the Invention
The present invention is related to pipe organs and, more particularly, is directed towards an electronic data processing system designed to perform the relay function of a unit pipe organ.
2. Description of the Prior Art
A pipe organ is a musical instrument in which sound is produced by passing compressed air through pipes. The selection of the particular pipes is controlled by a console that comprises a number of keyboards, as well as a set of stops for each keyboard.
More particularly, the pipes of the organ are organized into a plurality of rows, called ranks, and a plurality of columns. Each rank represents a different tone type which may be produced by the particular organ, such as, for example, flute, diapason, violin, horn, and the like. Within each rank, each of the pipes has a different length, in order to produce the different notes within the particular tone type, and thus each rank contains at least 61 pipes (spanning 5 octaves and high C on a standard keyboard). Generally, however, most ranks contain more than 61 pipes, and means known as stops are provided on the console for selectively actuating a group of 61 pipes from within each rank for each keyboard, as will be explained in greater detail below. Within each rank, the pipes are also generally arranged in order of ascending pitch (descending length), with the first pipe being the longest pipe in the rank. Each set of pipes sits on a wind box or chest, and each pipe has its own magnetically controlled valve which, when actuated, allows air into the pipe.
On the console are provided a plurality of keyboards which generally include at least one keyboard playable by the feet called the pedal and a number of keyboards playable by the hands which are called manuals. The keys on the keyboards are arranged into groups of 12 and are labeled within each group C, C.music-sharp., D, D.music-sharp., E, F, F.music-sharp., G, G.music-sharp., A, A.music-sharp., and B. Each succeeding group of 12 keys plays notes one octave higher than the preceding group. Typical pedal keyboards contain 32 keys which span two and one-half octaves, while typical manual keyboards contain 61 keys spanning five full octaves plus high C.
Each keyboard has its own set of stops associated therewith. Generally, each stop controls one rank of pipes playable on its keyboard. Turning a stop ON allows the 61 (or 32) keys on its keyboard to control 61 (or 32) corresponding pipes of the rank identified by the stop. When the stop is OFF, playing of a key on its associated keyboard will not effect any of the pipes in the rank of that stop, assuming no other stops in that rank are activated. Stops are labeled by the rank they control (e.g., flute, horn, etc.) and by the pitch of the lowest note of the set of pipes they control. The pitch labels are indicated by the approximate length of the lowest pitch pipe (longest length) in the set, and typical pitches are 32', 16', 8', 4', and the like.
In operation, the organist selects the tones and pitches he wishes to use for each keyboard by turning the corresponding stops ON. Then, when a key is pressed, all of the pipes corresponding to that key and the selected ranks and pitches will be sounded. When the key is released, all of those pipes will stop sounding, even though the stops remain actuated. It therefore may be appreciated that the stop switches and the key switches may be thought of as being connected in series such that both must be closed in order to actuate the corresponding pipe.
The basic structure of a pipe organ is schematically illustrated in FIG. 1 wherein reference numeral 12 designates the console having M keyboards 18 and i stops 20, reference numeral 14 designates the pipes arranged in m rows and n columns, reference numeral 16 indicates the wind chests having coil magnets for each of the potential (m.times.n) pipes, and reference numeral 10 indicates a set of relays which transform the key-stop combinations designated on a console 12 into signals for actuating the appropriate coil magnets 16 to sound the corresponding pipes 14.
A unit pipe organ is one in which the same set of pipes may be controlled from several keyboards and at several different pitches. Thus, referring to FIG. 1, rank 3 is playable at 16' pitch on both keyboard 1 and keyboard 2, and in addition rank 3 may be played at 8' on keyboard M. If, for example, stop S3 is actuated, the 61 keys on keyboard 1 will cause pipes in columns 1 through 61 in rank 3 to sound, respectively, assuming that the lowest pitch pipe in rank 3 is 16'. The same sounds would be produced by actuating stop S6 and hitting the corresponding keys on keyboard 2. In contrast, actuation of stop S10 will enable the pipes in columns 13 through 73 of rank 3, since stop S10 is an 8' stop and begins therefore exactly one octave above stops S3 and S6. Thus, the 61 keys of keyboard M will serve to actuate pipes 13 through 73, respectively, in rank 3. If both stops S6 and S10 are enabled, actuation of the 13th key on keyboard 2 simultaneous with the actuation of the first key on keyboard M will cause the same pipe (rank 3, column 13) to play. Naturally, the stops, keyboards and pipes illustrated in FIG. 1 are simplified for the sake of explanation; clearly, many other stops-key combinations and configurations are possible.
As explained above, the relays 10 illustrated in FIG. 1 perform the function of actuating the proper electromagnet in unit 16 in response to designated stop-key combinations on console 12. Mathematically, the relays may be said to perform an AND operation between the stops and the keys, and then an OR operation among all the stop-key combinations that can affect each pipe. Two forms of such relays are in known use today.
The traditional form of relay system includes electromechanical devices. Each stop operates a gang switch that closes 61 (or 32) switches in parallel. These closed switches act as one input to what may be thought of as a mechanical AND gate. The other input comes from the keys on the keyboard. The back sides of the gang switches are connected to common buses that lead to the pipes. Thus, turning a stop on and pressing a key will produce a TRUE output signal from the AND gate which is sent to the corresponding pipe. Since, in a unit organ, there may exist many of such true signals from different stop-key combinations for a given pipe, they are each tied to a common bus, in what may be thought of as a mechanical OR gate, that leads to the pipes.
In such electromechanical systems, the magnets that allow air to the pipes are driven directly by the bus. Moreover, the contacts are all open air contacts. This, in turn, requires spreader relays to be used for the keys, and also calls for fairly high quality material to be used throughout, which in turn makes electromechanical relays relatively expensive.
Electromechanical systems are also quite large. For example, a typical keyboard relay will occupy a space many feet square by a foot deep. This size is due in part to the large number of individual wires that interconnect the keyboard relay to the gang switches. For example, for a manual keyboard having 15 stops, there are 61 wires leading from the keyboard to the relay, and (15.times.61)=915 wires leading to the gang switches. Typical gang switches are 10 to 12 inches long and several inches high. Since a moderately sized organ can have a hundred stops, and hence a hundred gang switches, this section of the total relay can also occupy many cubic feet, again requiring space enough for (100.times.61)=6,100 wires leading in, and one wire leading out for each pipe. In larger unit organs, the two sections (the keyboard relay and the gang switches) can occupy an entire room.
Recently, systems that replace the mechanical devices with integrated electronic circuits have been marketed. Such circuits adhere to the basic design set forth above, except that electronic AND gates replace the key-to-gang switch connections, and OR gates tie the AND outputs to a signal to the pipe. Clearly, for a one hundred stop organ, 6,100 individual AND gates and a large number of OR gates are required, in addition to circuit boards, and the like, which tends to make the electronic systems also somewhat expensive.
I am aware of several U.S. patents which teach the utilization of electronic circuitry for pipe organs. For example, U.S. Patents to Wick and Burton (Nos. 3,138,052 and 3,379,085) teach the utilization of transistors and related circuitry to actually drive the coils in place of the mechanical, open-air switches of the prior art.
Other U.S. patents deal with combination actions, which are devices that change the stop settings in response to the actuation of a member known as a piston. Pistons permit the organist to change the stop setting during the performance of a piece of music in order to achieve a different sound quality. Since such a change may involve 30 to 50 or more stops, electromechanical pistons were evolved to permit the stops of all be changed in an instant. U.S. Patents to Oncley (No. 3,548,064), Badessa (No. 3,686,994), Denigan et al (No. 3,699,839), and Molnar (3,700,784 and 3,733,593) all relate to the replacement of such electromechanical devices by solid state electronic devices for effecting a change in stop settings when a piston is pressed. The U.S. Patent to Griffis (No. 3,926,087) utilizes a programmed computer for this purpose, and some of the patents include a means for changing the memory (i.e., means for changing the pattern of ON and OFF stops for each piston).
The U.S. Patent to Jappe et al (No. 3,501,990) deals with the replacement of electromechanical relays by solid state devices. More particularly, Jappe et al utilize a set of 61 transistors to replace the 61 contact mechanical gang switches of the relays. The emitters of all 61 transistors are connected to the stop. The collectors of the various transistors from different keys that control the same pipe are also interconnected, and each key must be connected to the bases of as many transistors as there are stops for that keyboard. Closing a particular stops connects all 61 emitters to a source. Then, when a key is played, the transistor in series therewith is energized to actuate the series connected coil. While an improvement over electromechanical devices, the solid state type of relay taught by Jappe et al still requires 61 transistors for every stop, thereby leading in turn to complex wiring schemes and attendant high costs.
I am also aware of U.S. Pat. No. 3,903,778 to Ferch which teaches electronic couplings and actuation circuits for a multi-keyboard instrument.